Energetic properties and testing methodologies of oxidising substances

Transcription

1 Enabling a better working world Energetic properties and testing methodologies of oxidising substances Miss Anna Martínez MSc AMRSC Dr Stephen R Graham UK-ELG Meeting Explosion Data Generation Health and Safety Laboratory (HSL, Buxton) 23 April 2015

2 1. Oxidising substances Substances or mixtures which, while in themselves not necessarily combustible, may, generally by yielding oxygen, cause, or contribute to, the combustion of other materials. (Regulation (EC) No 1272/2008 The CLP regulation) High reactivity: due to their oxygen content. No external ignition source required for combustion. Considers organic peroxides (H 2 O 2 derivatives) O-O- Liable to explosive decomposition if contaminated.

3 2. Hazardous Substance Consent (HSC): HSC application for Land-Use Planning (LUP) purposes. LUP Consultation zones HSE Guidance: assessment of the overall explosive yield for the quantity of oxidising substances stored. Current oxidiser assessments require HSL / HSE expert assessment on a case by case basis

4 2. Hazardous Substance Consent (HSC): Worst-case contaminant scenario: Oxidiser + non-explosive substance to produce the worst case explosive overpressure by detonation. Quantification equivalent to a mass of TNT: TNT mass equivalent = Explosive power Explosion efficiency Mass oxidiser For generic oxidisers, worst-case exemplar: 89% Hydrogen peroxide; explosive yield = 0.69

5 Oxidiser League table 3. Oxidiser League Table: Proposal Oxidising substances (Great Britain) Classification criteria Category 1 Category 2 Category 3 Category 4 Exemplar 1 Exemplar 2 Exemplar 3 Exemplar 4

6 Oxidiser League Table 3. Oxidiser League Table: List compilation Compilation of a of list of oxidisers commonly used in GB. Trade bodies and associations in GB: CEFIC, CIA. International bodies: IGUS-EOS Group DATATOP 2013 HSE Records (TRIM). Survey HSE Inspectors specialized in risk assessment. Planning Regulations for Hazardous Substances (2009). UN Manual of Test and Criteria

7 3. Oxidiser League Table: List generation Refined list of oxidisers arranged by: UN Class (5.1, 5.2, others risks) Tonnage Frequency Apparent lack of available explosive power data, specially for standard oxidisers. DATATOP 2013 Exclusive to OP UN Test F.1 Ballistic Mortar Mk III few OP

8 4. Other classification criterion Consistent criterion to cover all (or most) of the oxidisers included in the refined list obtained. Packing group (UN Manual) Hazard Rating (NFPA 704) NFPA 430 Code for the storage of Liquid and Solid Oxidisers

9 5. NPFA 430 Code Class CLASS 1 CLASS 2 CLASS 3 CLASS 4 Criteria Does not moderately increase the burning rate of combustible materials with which it comes into contact. Causes a moderate increase in the burning rate of combustible materials with which it comes into contact. Causes a severe increase in the burning rate of combustible materials with which it comes into contact. Generally meets the Class 3 criteria plus can undergo an explosive reaction due to contamination or exposure to thermal or physical shock with which it comes into contact. Flammability criteria

10 6. HSE CS21 Guidance Type Type 1 Type 2 Type 3 Type 4 Criteria This contains both explosive-labelled packaged peroxides and packaged peroxides which burn very intensely. This contains packaged peroxides which burn in a way which is intermediate between Type 1 and 3. This contains packaged peroxides which burn in the range gently up to something akin to solvents and hydrocarbons. This contains packaged peroxides which are non-combustible and from which the available oxygen is not more than 5%. Flammability criteria

11 7. Flammability type classification criteria Oxidising substances: NFPA 430 Code Organic peroxides: HSE CS21 Guidance

12 8. Conclusions The oxidiser league table is a practical concept. Shortage of available explosive yield data. Arrangement by burning rate is possible and allows some fit with other international systems. No correlation proven between burning rate and explosive yield.

13 9. Future work: Oxidising substances Characterization: Experimental test campaign. Carius tube Ballistic Mortar MKIII Test of oxidisers when contaminated. Use of paraffin wax (C n H 2n+2 ) instead of cellulose. Paraffin at certain temperature improves the mixing oxidiser contaminant. Mixing independent of the particle size.

14 9. Future work: Oxidising substances Correlation burning rate explosive yield Classification

15 Thank you for your time! Edmund Cowpe Specialist Inspector, Hazardous Installations Directorate, CI5H Dr Stephen R Graham Hazardous Substances Team Leader, Major Hazards Unit stephen.graham@hsl.gsi.gov.uk Anna Martínez MSc AMRSC Scientist, Major Hazards Unit anna.martinez@hsl.gsi.gov.uk